Matching Items (4)
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- All Subjects: Bacteria
- Creators: Alum, Absar
Description
Nanotechnology is a scientific field that has recently expanded due to its applications in pharmaceutical and personal care products, industry and agriculture. As result of this unprecedented growth, nanoparticles (NPs) have become a significant environmental contaminant, with potential to impact various forms of life in environment. Metal nanoparticles (mNPs) exhibit unique properties such as increased chemical reactivity due to high specific surface area to volume ratios. Bacteria play a major role in many natural and engineered biogeochemical reactions in wastewater treatment plants and other environmental compartments. I have evaluated the laboratory isolates of E. coli, Bacillus, Alcaligenes, Pseudomonas; wastewater isolates of E. coli and Bacillus; and pathogenic isolate of E. coli for their response to 50 & 100 nm sized Cu nanoparticles (CuNPs). Bactericidal tests, scanning electron microscopy (SEM) analyses, and probable toxicity pathways assays were performed. The results indicate that under continuous mixing conditions, CuNPs are effective in inactivation of the selected bacterial isolates. In general, exposure to CuNPs resulted in 4 to >6 log reduction in bacterial population within 2 hours. Based on the GR, LDH and MTT assays, bacterial cells showed different toxicity elicitation pathways after exposure to CuNPs. Therefore, it can be concluded that the laboratory isolates are good candidates for predicting the behavior of environmental isolates exposed to CuNPs. Also, high inactivation values recorded in this study suggest that the presence of CuNPs in different environmental compartments may have an impact on pollutants attenuation and wastewater biological treatment processes. These results point towards the need for an in depth investigation of the impact of NPs on the biological processes; and long-term effect of high load of NPs on the stability of aquatic and terrestrial ecologies.
ContributorsAlboloushi, Ali (Author) / Abbaszadegan, Morteza (Thesis advisor) / Alum, Absar (Committee member) / Fox, Peter (Committee member) / Olson, Larry (Committee member) / Arizona State University (Publisher)
Created2012
Description
The purpose of this study was to determine the applicability of fluorescent microspheres as a surrogate to measure the removal of Cryptosporidium oocysts through the coagulation, flocculation, sedimentation, and filtration steps of conventional water treatment. In order to maintain accuracy and applicability, a local water treatment facility was chosen as the system to model. The city of Chandler Arizona utilizes conventional treatment methodologies to remove pathogens from municipal drinking water and thus the water, coagulant, polymer, and doses concentrations were sourced directly from the plant. Jar testing was performed on four combinations of coagulant, polymer, and fluorescent microsphere to determine if the log removal was similar to that of Cryptosporidium oocysts.
Complications with the material properties of the microspheres arose during testing that ultimately yielded unfavorable but conclusive results. Log removal of microspheres did not increase with added coagulant in the predicted manner, though the beads were seen aggregating, the low density of the particles made the sedimentation step inefficient. This result can be explained by the low density of the microspheres as well as the potential presence of residual coagulant present in the system. Given the unfavorable properties of the beads, they do not appear to be a suitable candidate for the surrogacy of Cryptosporidium oocysts in conventional drinking water treatment. The beads in their current state are not an adequate surrogate; however, future testing has been outlined to modify the experiment in such a way that the microspheres should behave like oocysts in terms of physical transportation.
Complications with the material properties of the microspheres arose during testing that ultimately yielded unfavorable but conclusive results. Log removal of microspheres did not increase with added coagulant in the predicted manner, though the beads were seen aggregating, the low density of the particles made the sedimentation step inefficient. This result can be explained by the low density of the microspheres as well as the potential presence of residual coagulant present in the system. Given the unfavorable properties of the beads, they do not appear to be a suitable candidate for the surrogacy of Cryptosporidium oocysts in conventional drinking water treatment. The beads in their current state are not an adequate surrogate; however, future testing has been outlined to modify the experiment in such a way that the microspheres should behave like oocysts in terms of physical transportation.
ContributorsLinks, Alexander Glenn (Author) / Abbaszadegan, Morteza (Thesis advisor) / Alum, Absar (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2015
Description
The impact of physical/chemical properties of gray water on microbial inactivation in gray water using chlorine was investigated through creating artificial gray water in lab, varying specific components, and then measuring microbial inactivation. Gray water was made through taking autoclaved nanopure water, and increasing the concentration of surfacants, the turbidity, the concentration of organic content, and spiking E. coli grown in tryptic soy broth (TSB); chlorine was introduced using Clorox Disinfecting Bleach2. Bacteria was detected using tryptic soy agar (TSA), and E. coli was specifically detected using the selective media, brilliance. The log inactivation of bacteria detected using TSA was shown to be inversely related to the turbidity of the solution. Complete inactivation of E. coli concentrations between 104-105 CFU/100 ml in gray water with turbidities between 10-100 NTU, 0.1-0.5 mg/L of humic acid, and 0.1 ml of Dawn Ultra, was shown to occur, as detected by brilliance, at chlorine concentrations of 1-2 mg/L within 30 seconds. These result in concentration time (CT) values between 0.5-1 mg/L·min. Under the same gray water conditions, and an E. coli concentration of 104 CFU/100 ml and a chlorine concentration of 0.01 mg/L, complete inactivation was shown to occur in all trials within two minutes. These result in CT values ranging from 0.005 to 0.02. The turbidity and humic acid concentration were shown to be inversely related to the log inactivation and directly related to the CT value. This study shows that chlorination is a valid method of treatment of gray water for certain irrigation reuses.
ContributorsGreenberg, Samuel Gabe (Author) / Abbaszadegan, Morteza (Thesis director) / Schoepf, Jared (Committee member) / Alum, Absar (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Nitrogen removal and energy reduction in wastewater treatment are shared goals. Approaches to achieve those goals include the techniques of shortcut nitrogen removal utilizing nitrite shunt, biocatalyst, nitritation, deammonification, and simultaneous nitrification-denitrification. The practice of those techniques is newer in the industry of wastewater treatment but continues to develop, along with the understanding of the biological and chemical activities that drive those processes. The kinetics and stoichiometry of traditional and shortcut nitrogen removal reactions are generally well understood to date. However, the thermodynamics of those processes are complex and deserve additional research to better understand the dominant factors that drive cell synthesis. Additionally, the implementation of nitrogen shortcut techniques can reduce the footprint of wastewater treatment processes that implement nitrogen removal by approximately 5 percent and can reduce operating costs by between 12 and 26 percent annually. Combined, nitrogen shortcut techniques can contribute to significant reduction in the long-term cost to operate, due to lower energy and consumable requirements, fast reaction times resulting in shorter solids retention times, and improvement efficiency in nitrogen removal from wastewater. This dissertation explores and defines the dominant factors that contribute to the success of efficiencies in traditional and shortcut nitrogen removal techniques, focusing on the natural microbiological processes. The culmination of these efforts was used to develop decision matrices to promote consideration of nitrogen shortcut techniques by practitioners during conceptual planning and design of wastewater treatment facilities.
ContributorsTack, Frederick Henry (Author) / Fox, Peter (Thesis advisor) / Krajmalnik-Brown, Rosa (Committee member) / Abbaszadegan, Morteza (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2021